The present invention is a fluidizing chamber, cannula and duckbill check valve and swiveling quick disconnect assembly. It differs from the predecessor invention disclosed and claimed in the immediately prior parent application by, among other things, the elimination of the double function check valve feature, that was any one of at three possible configurations. The internal duckbill check valve is retained from one of those configurations as a single acting feature to prevent backflow of particulate matter when the chamber is disconnected from the pressurized fluid source or there is a drop in pressure from said source. Also added is a swiveling quick disconnect. The invention comes in two embodiments—one is refillable and includes detachable cannula, while the other includes a prefilled, sealed, and disposable fluidizing chamber with fixedly attached cannula that is disposed with the empty fluidizing chamber.
The duckbill valve is placed on the discharge end of the inlet tube disposed within the fluidizing chamber. It is made of a resiliently flexible material and formed with a bullet nose shape with a slit at the nose. The duckbill valve is normally closed due to the natural molded shape of the part and the shape memory of the material from which it is formed. In use the fluid pressure required to operate the valve is sufficiently strong to open the “jaws” of the slit allowing for full flow of the fluid. As the pressure is reduced or eliminated, the jaws naturally close as a result of the elastic memory of the material. This prevents backflow of the particulate matter.
Earlier designs of pressurized particulate matter delivery devices have demonstrated there can be difficulty with clogging in the fluidizing chamber and/or the delivery tube. The present invention is partially directed to an improved internal structure of the fluidizing chamber which produces effective fluidization without clogging.
The swiveling quick disconnect is intended to be in fluid communication with a pneumatic pressure line that is operated on and off by a control apparatus that may optionally be in the form of a foot pedal. When used in the dental profession, connection is to the pneumatic pressure line of a dental office pedestal. Since this control apparatus technology is well known, it is not disclosed and is referred to as conventional.
Another feature of the general utility (non-dental) use embodiment of the invention includes a disposable cannula that preferably includes a tapered nozzle (which may be really a disposable hypodermic needle) which can be detached from the refillable fluidizing chamber. Detachment is important because since the fluidizing chamber can be perpetually refilled. Therefore, the cannula will need to be replaced regularly, since the grit is abrasive and wears out the cannula more quickly than other components in the inventive assembly. Detachment also facilitates optional availability of a plurality of differing tips to accommodate differing grit sizes and different pressure in the fluidizing chamber for a variety of different uses. Also available are bent particle delivery cannula, which are furnished bent at a 45 degree angle or a 90 degree angle.
Examples of prior known devices include that described in U.S. Pat. No. 4,941,298 to Fernwood, which discloses a rear-reservoir micro sandblaster. The Fernwood patent has numerous problems including costly to dispose, special training for set up and use, and cannot deliver varying sizes of particles. Other known devices with similar problems are the Microetcher™ and the Handiblaster™ available from Mirage/Chameleon Dental Products, Inc.